Package testing

ABSTRACT

A package is conveyed to a test station where a friction roller is pressed against the package and urged to rotate relative to the package. The amount of rotation urgeable for a preset torque is indicative of package seal quality. This rotation is automatically detected and compared with a preset value to determine the quality of the package seal.

BACKGROUND

This invention relates to a machine and method that may be used forapplying a non-destructive test to a package such as a vacuum package,containing, for example, food, chemicals or medicines. This may be tocheck that the sealing of the package is good, e.g. so that the productwithin the package cannot escape from the package; nor can the outsideatmosphere enter the package. It is particularly applicable to packageshaving flexible outer layers of plastics films.

A machine of such type is useful, for example, in production lines,where it would be desirable to verify the integrity of the seals of thecomplete production throughput without destroying the packages orproducts.

SUMMARY

According to the invention there is provided a apparatus for testingpackages comprising:

a test station having support means for supporting a package;

a test probe arranged to be relatively reciprocable towards and awayfrom the support means; said probe having a surface portion which istransversely displaceable;

first urging means for urging relative movement of the probe towards thesupport means to contact with its displaceable surface portion a packagesupported at said test station;

second urging means to urge said transverse displacement of said probesurface portion; and

means for detecting transverse displacement of the probe surface portionand providing a corresponding output signal; whereby the probe isurgeable by said first urging means to contact a package at the teststation with its surface portion, whereupon the ability of the secondurging means to displace the probe surface portion is dependent on thenature of he contacted package, so that the output signal of thedetecting means is indicative of package quality.

The apparatus may test a stationary package. Dynamic testing is alsopossible, with packages moving continuously through one or more teststations.

In another aspect the invention provides a method of testing a packagecomprising applying a test probe to the package; urging transversedisplacement of a surface portion of the probe relative to the packagewhile restraining displacement of the package in response thereto; anddetermining the amount of displacement of the probe surface portionrelative to the package and providing a corresponding output signalindicative of package quality.

The force and/or torque applied by the probe may be variable.

In order that the invention may be more clearly understood someembodiments will now be described with reference to the accompanyingdrawings wherein:

BRIEF DESCRIPTION

FIG. 1 is a perspective view of a first embodiment;

FIG. 2 is a schematic side view of a second embodiment having two teststations; and

FIG. 3 is a front view of a test station of the second embodiment.

DETAILED DESCRIPTION

FIG. 1 shows an automatic conveying and seal integrity testing systemhaving the means to receive a packaged product from an upstream machine,such as a fill and seal machine, via a feed conveyor 4, into a testarea. A machine frame comprises side plates 13 adjacent the feedconveyor 4. One side plate 13 carries an arm assembly including arotatable shaft 3 which is urgeable towards the surface of the conveyor4 to contact an article, such as a package 1, thereon. The shaft 3carries a test roller 3' with a high-friction surface. The shaft isrotatably and driveably mounted in a test arm 14 which is displaceableby an actuator 5. It is rotatable by a second actuator 6, as explainedbelow.

The arrival of a package is sensed by a sensor 2 which signals acomputer 10 to operate the displacement actuator 5. Actuator 5 operatesonly after an adequate amount of time has passed to allow the packagedue to be tested to arrive centrally under the test roller 3'.

The complete test function is automatic, with timed signals being sentto all the actuators, forcing a sequence of operations. For example,conveyor 4, which has a conveyor surface with gripping qualities, stopsmomentarily when package 1 arrives centrally under test roller 3' toallow the test to be applied. The actuator 5 then pulls test arm 14downwards, forcing test roller 3' into contact with the top layer of thepackaging material of package 1. The gripping qualities enable theconveyor belt fitted to conveyor 4 to hold the package 1 in a fixedposition during the test. Rotation actuator 6 pulls test shaft plate 22,forcing test shaft 3 and test roller 3' to turn in an anti-clockwisedirection. The amount that test roller 3' is allowed to rotate isdetermined by the nature of the surface of the package, particularly theseal quality. It is monitored by an incremental encoder 7 whose outputis fed through a bi-directional module 8 to a digital input counter 9which displays the count on its digital display panel.

Prior to a production run, an optimum or ideal package is selected andis fed into the testing station, where a seal test is applied and areference reading is taken. This reference reading plus a tolerance banddetermined by the machine user, is keyed into a data access unit of thecomputer. This then becomes the standard to which all subsequentpackages are compared. Production is then allowed to commence with anysubsequent package that fails to meet this pre-set standard beingrejected.

The reading from each and every test is compared to the preset standard.Any package 1 that is found to be within the preset standard is allowedto continue through to the next in-line machine via the outfeed conveyor11. Any package 1 failing to meet the preset standard is rejected fromthe line by reject mechanism 12. The reject mechanism 12 shown is an airjet, but could be a mechanical, electrical or pneumatic actuator.

The amount of rotation that test roller 3 achieves during testing of thepackage 1 is determined by the resistance offered by the package 1 beingtested. A package with good seals offers a greater resistance than apackage with leaking seals. Also, packages with good seals tend to offera consistent level of resistance from package to package, whereas apackage with bad seals tends to offer considerably less resistance andtherefore produces a greater reading than the pre-set standard.

The displacement actuator 5 is fitted to conveyor side 13 and to testarm 14 in such a way, via pivot points 16 and 18, as to allow it topivot during operation.

The rotation actuator 6 is fitted to test arm 14 and test roller shaftplate 22 in such a way, via pivot points 17 and 19, as to allow it topivot during operation.

Test roller shaft 3 may be mounted via a one way bearing 23. Thisensures that test roller shaft 3 will only rotate in an anti-clockwisedirection against the flow of packages 1.

Test arm 14 is fitted to conveyor side 13 in such a way, via pivot point15, as to allow it to pivot during operation.

Test roller 3 has a surface with a multiplicity of grooves, and has ahigh-friction coating applied by means of a rubber solution. Thus itoffers a high level of grip to the packaging material used in package 1.

Test roller 3' is fitted and locked onto shaft 3 which is fitted throughincremental encoder 7 to one way bearing 23.

Shaft 3' may be free running in one direction only, as allowed by oneway bearing 23.

The height that test roller 3' is set above conveyor 4 can be varied byadjusting the position of pivot point pillar 25, via a slot 20 in theconveyor side 13. This allows a wide range of heights of packages 1 tobe tested, for example, at the lowest adjustment a flat package of "D"shaped ham with a package height of less than 3 mm can be tested. At thehighest adjustment a package such as a cheese block with a height of 90mm or greater can be tested. This is a manual method of adjustment;however, it could easily be made automatic by fitting an actuator toraise and lower the pivot point pillar 25.

FIGS. 2 and 3 show a second embodiment having a multiplicity (in thisexample two) of testing stations. The testing stations are arranged toapply tests to moving products 101 carried on a conveyor 104.

Generally as described with reference to FIG. 1, there are a data accessunit 100 linked to a computer 110 having the means to set a presetstandard of quality of seal to a packaged product that all subsequentlytested packages have to be within, and means to receive a packagedproduct 101 from an upstream machine, such as a fill and seal machine,not shown, via a feed conveyor 104. The arrival of the package at thefirst roller assembly test station 112 is sensed by a sensor 102. Thissignals computer 110 to operate an actuator 122 to move a rollerassembly 132 downwards to arrive onto package 101. The amount ofpressure applied by roller assembly 132 during the test can be alteredand preset to suit the type of packaged product being tested. Whenroller 103 (which has a high grip surface, for example rubber) comesinto contact with a package 101, the roller 103 will be forced to rotateby product 101 as it is conveyed beneath it by conveyor 104. The amountof rotation of roller 103 is monitored by encoder 128. At apredetermined position, for example, when the package 101 has arrivedcentrally beneath test roller 103, a valve or actuator 126 is made tooperate by computer 110 to force roller 103 to turn in a clockwisedirection against the direction of flow of package 101. If a package 101has a good seal, it will overcome the level of force being applied byactuator 126 via roller 103. The resulting reading of the test byencoder 128 will be a reading that matches or is within the presetstandard. This package 101 may at this point, without further testing,be regarded as a package with a good seal or a further seal test may beapplied at a further test station 133, using the same method of testingas at the first test station 112. The result is compared by the computer110 with the test applied by the first test station 112. This dual testwill also be compared against the preset standard. If the resultingreading shows that the package 101 is within the preset standard andthat the comparison between the tests at the two test stations showsthat the results are the same, or differ by less than a presetdifference band value, the package will be allowed through to the nextin-line machine for the next stage of the production and packagingprocess.

However, if package 101 has a bad or leaking seal at the first teststation 112 the force being applied by actuator 126 and roller 103 willnot be resisted by the package. A shear action will occur between thetop and bottom films of package 101. The resulting reading of the testby encoder 128 will be a reading that is outside the preset standard.This package 101 may at this point, without further testing be regardedas a package with a bad seal or a further seal test may be applied atthe second test station 133 and compared with the test applied by thefirst test station 122. This dual test will also be compared against thepreset standard. If the resulting readings show that package 101 isoutside the preset standard or that the comparison between the tests attest stations 112 and 133 are significantly different, then package 101will be rejected by reject means such as, for example, air jet 109.

Actuator 122 is fixed to a supporting non moving frame, not shown. Thefirst test station 122 has a piston/cylinder assembly with a piston 115to which the roller assembly 132 is mounted so as to allow it to belowered by the downward stroke of actuator 122 onto a package, and alsoremoved back to the starting position by the back stroke of actuator122. Shaft 137 passes through roller 103 and encoder 138 and issupported both ends by bearing block 144.

Test roller 103 is keyed to shaft 137. Encoder 128 is keyed to shaft137. The linear measuring device of encoder 128 is allowed to rotatewith roller 103 in either direction. The housing of encoder 128 is fixedto bearing block 144, which is fixed in the test station 122. The outercasing of drive means 126 which for example could be a motor or a rotaryactuator is fixed to bearing block 144 allowing the inner drive which iskeyed to shaft 137 to rotate in any direction.

The second test station 133 and any other test stations are mounted andassembled in the same way as described above. All of the test stationsare mounted independently of each other.

What is claimed is:
 1. Apparatus for testing packages comprising:a teststation having support means for supporting a package; a test probearranged to be relatively reciprocable towards and away from the supportmeans; said probe having a surface portion which is transverselydisplaceable first urging means for urging relative movement of theprobe towards the support means to cause said transversely displaceablesurface portion to contact a package supported at said test station;second urging means to urge said transverse displacement of said probesurface portion; and means for detecting transverse displacement of theprobe surface portion and providing a corresponding output signal; saidprobe being urgeable by said first urging means to contact a package atthe test station with said transversely displaceable surface portion,whereupon the ability of the second urging means to displace saidtransversely displaceable surface portion is dependent on the nature ofthe contacted package, so that the output signal of the detecting meansis indicative of package quality.
 2. Apparatus according to claim 1wherein said transversely displaceable test probe surface portioncomprises a rotary element.
 3. Apparatus according to claim 1 whereinthe support means and the transversely displaceable probe surfaceportion have grip surfaces adapted to engage a package with highfriction.
 4. Apparatus according to claim 1 including conveyor means forconveying packages to and from the test station.
 5. Apparatus accordingto claim 4 wherein the conveyor means has a displaceable support surfacewhich also provides said support means.
 6. Apparatus according to claim4 arranged to test a package while it is being conveyed by the conveyormeans.
 7. Apparatus according to claim 1 further comprising computermeans arranged to receive the output signal of the detecting means andcompare it with a preset value or range.
 8. Apparatus according to claim7 further comprising package rejecting means arranged to be actuable bysaid computer means in response to a comparison.
 9. Apparatus accordingto claim 1 having a plurality of test stations, each having a respectiveassociated test probe, first and second urging means, and displacementdetecting means.
 10. Apparatus according to claim 1 wherein the firsturging means is adjustable to allow for different package thickness. 11.A method of testing a package comprising applying a surface portion of atest probe to a package; urging transverse displacement of the surfaceportion of the probe relative to the package while restrainingdisplacement of the package in response thereto; determining the amountof displacement of the probe surface portion relative to the package;and providing an output signal corresponding to the amount ofdisplacement and indicative of package quality.